It is well known to use plastic or metal caps to seal either glass or plastic containers having typical wall and mouth configurations. In particular, with glass bottles, it has been necessary to design the cap with relatively rigid internal sealing configurations so as to accomodate the imperfections typically found in the mouth of glass bottles as a result of the manufacturing process or rough handling thereafter.
In order to provide for improved sealing characteristics, caps have been constructed with internal threads which cooperate with like threads formed on the outer surface of the mouth of the container. Nevertheless, the sealing provided by such threads is not adequate for most uses. Such threaded configuration also not only renders the construction of the cap more difficult but increases the cost of construction as well.
However, removing the threads thereby also removes some of the sealing surfaces. For this reason, it is desirable to compensate for such sealing loss.
Additionally, it is desirable to render the cap tamper-proof so as to be able to discourage or give evidence of any unauthorized removal or prying off of the cap. For this reason, skirts are usually provided about the lower edge of the cap to provide an added feature of security. Such frangible skirts are disclosed in U.S. Pat. Nos. 3,109,547; 3,622,028; 3,940,004; 3,991,904; 3,994,409; 4,066,182; 4,162,736; and 4,166,552.
Before the cap can be removed from the mouth of the container which is sealed by the cap, it is necessary to first separate the skirt from the cap before proceeding with the removal of the cap. Typically, these skirts extend downwardly away from the lower edge of the cap. Inspection of the integrity of the skirt will readily indicate whether unauthorized removal of the cap may have occurred. Such unauthorized removal may be attempted by inserting a fingernail or other suitable implement such as the edge of a screwdriver under the edge of the cap. If such prying is attempted, the skirt usually will break away from the edge of the cap and thus serve as an indication of the tampering.
Notwithstanding the improvements offered by the closure caps disclosed in the above-noted patents, certain of these closure caps suffer from certain disadvantage in that it is possible to pry off the cap and frangible skirt together in one motion without causing any damage or separation of the skirt from the major portion of the cap itself. Additionally, the structure of these caps is such that inadvertent prying off of the cap or separation of the skirt from the remaining portion of the cap may occur when any protruding portion of the skirt is caught by nearby objects.
I have invented a snap-on cap, which together with a container having a suitably configured mouth, provides an improved sealing of the container mouth in combination with the inner sealing characteristics of the snap-on tamper proof closure cap. In addition, I have invented a tamper proof cap which assures relatively more positive identification of intentional or inadvertent prying of the cap off the container. Also, the tamper proof cap which I have invented discourages such intentional prying and furthermore safeguards against inadvertent prying.